The neurobiology of sexual behavior involves the interrelationships between sex steroids and neurotransmitters that result in both central nervous system (CNS) effects and effects in the genitalia. Tools such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) scanning can help determine what areas of the brain are activated under sexual stimulation. Our understanding of the role of various neurotransmitters, neurosteroids and other CNS-acting compounds is improving. The role of CNS-acting compounds such as dopamine agonists in the treatment of male sexual dysfunction is under active investigation. Melanocortins have CNS and peripheral roles in a wide variety of bodily functions. The melanocortin agonist bremelanotide appears to act in the CNS to promote erections in preclinical models, and may also stimulate behaviors that facilitate sexual activity beyond their erectogenic effects.